In conventional sunshields for use in association with the rear window of an automobile, a structure is usually provided which utilizes a number of slats or louvers fastened to a frame. The louvers are aligned substantially parallel to each other and with a generally horizontal orientation. This disposition reduces significantly the amount of direct sunlight passing through the rear windshield of the automobile. This is particularly desirable when used with slantback or hatchback automobiles in which the rear window has a very substantial horizontal component of orientation. The horizontal disposition of the louvers allows the vehicle occupants to look through the rear window of the automobile without a significant obstruction to their view.
Conventional sunshields, however, entail several disadvantages. They are usually formed with metal louvers which are attached to a framework that is fitted to the rear window of the vehicle. These sunshields are usually formed from a multiplicity of separate parts involving louver sections, frame sections, and vertical struts, all of which must be assembled together to form the complete structure. In addition, the metal louvers become quite hot in a direct sunlight, and so will burn the hand of any person inadvertently touching them.
The formation of sunshields for the rear windows of automobiles has been attempted using a single sheet of deformable material as the operative structure. However, the deformable material of choice is generally plastic, and the resultant sunshields formed in this manner have heretofore been structurally unsound. The structural inadequacies of previous sunshields which have been formed from a single unitary plastic structure is attributable to the transverse instability of the louvers formed. That is, because of the relatively wide distance to be spanned by the louvers, across the width of the rear window, the flexibility of the plastic material produces elastic deflections of the louvers in a vertical direction. This is particularly pronounced when the vehicle is proceeding over a rough road or rough terrain.
Attempts have been made to form supporting spacers or uprights between the louvers to provide necessary structural rigidity. However, one implementation of structural design requires that the unitary sheet from which the sunshield is formed by lengthened by the aggregate length of such supporting columns between the louvers. This is wasteful since the material laterally adjoining these spacers or columns must be discarded to provide the necessary apertures between louvers. Alternatively elaborate and expensive molds must be employed to initially form the required apertures.
An alternative form of such a structure stretches the available material the requisite distance so that the necessary supports are formed. However, the result frequently is a sunshield in which the supports between louvers have been stretched so thin as to be of little use. They are easily broken and then provide an unsightly appearance along with failing to provide the vertical support for which they were intended.